Techniques have been known in which a seal is applied to an opening portion in order for traces to remain when unsealing a package of goods, and if the seal is broken once, it can be determined whether or not the seal has been broken. This seal is called a breakable seal. In a breakable seal, breakage of the breakable seal can be discriminated by optical changes thereof, that is, changes in appearance thereof.
A transferable seal and a nontransferable seal may be used as the breakable seal. In the transferable seal, when the transferable seal, which has been applied to an article, is forcibly peeled from the article, a portion of the transferable seal remains on the article. In the transferable seal, since traces by peeling the transferable seal from the article are generated on the article on which the transferable seal has been applied, it can be determined whether or not breaking of the transferable seal was performed. The transferable seal is disclosed in Patent Publications 1 and 2.
Although the non-transferable seal can be peeled from an article to which the nontransferable seal has been applied, traces by peeling the nontransferable seal from the article are generated on the article. When the nontransferable seal which was peeled therefrom is applied to the article again, it can be discriminated that the nontransferable seal which was peeled therefrom was applied to the article again. The nontransferable seal is disclosed in Patent Publications 3 to 5.
The Patent Publication 1 is Japanese Unexamined Patent Application Publication No. Hei 9-277423. The Patent Publication 2 is Japanese Unexamined Patent Application Publication No. Hei 8-95491. The Patent Publication 3 is Japanese Unexamined Patent Application Publication No. 2003-261840. The Patent Publication 4 is Japanese Unexamined Patent Application Publication No. 2003-84672. The Patent Publication 5 is Japanese Unexamined Patent Application Publication No. Hei 7-234636.